package io;
import java.util.regex.*;
import java.io.*;
import java.util.*;
public class DirList2 {
    public static FilenameFilter filter(final String regex){
        return new FilenameFilter() {
            private Pattern pattern=Pattern.compile(regex);
            @Override
            public boolean accept(File dir, String name) {
                return pattern.matcher(name).matches();
            }
        };
    }

    public static void main(String[] args) {
        File path=new File(".");
        String[] list;
        if(args.length==0)
            list=path.list();
        else
            list=path.list(filter(args[0]));
        Arrays.sort(list,String.CASE_INSENSITIVE_ORDER);
        for(String dirItem:list)
            System.out.println(dirItem);
    }
}
